Module resolution: Regression in JSON import using Node16 resolution

[raykyri]

Demo Repo

canvasxyz/canvas#405

Which of the following problems are you reporting?

Something else more complicated which I'll explain in more detail

Demonstrate the defect described above with a code sample.

import * as pkg from "../package.json"

Run tsc --showConfig and paste its output here

> cd examples/chat-explorer
> npx tsc --showConfig
{
    "compilerOptions": {
        "composite": true,
        "strict": true,
        "declaration": true,
        "module": "node16",
        "target": "es2020",
        "moduleResolution": "node16",
        "allowSyntheticDefaultImports": true,
        "useDefineForClassFields": true,
        "skipLibCheck": true,
        "rootDir": "./src",
        "outDir": "./lib",
        "lib": [
            "es2020",
            "dom",
            "dom.iterable"
        ],
        "jsx": "react-jsx",
        "noUnusedLocals": true,
        "noFallthroughCasesInSwitch": true,
        "resolveJsonModule": true,
        "moduleDetection": "force",
        "esModuleInterop": true,
        "resolvePackageJsonExports": true,
        "resolvePackageJsonImports": true,
        "incremental": true,
        "noImplicitAny": true,
        "noImplicitThis": true,
        "strictNullChecks": true,
        "strictFunctionTypes": true,
        "strictBindCallApply": true,
        "strictPropertyInitialization": true,
        "strictBuiltinIteratorReturn": true,
        "alwaysStrict": true,
        "useUnknownInCatchVariables": true
    },
    "references": [
        {
            "path": "../../packages/core"
        },
        {
            "path": "../../packages/chain-atp"
        },
        {
            "path": "../../packages/chain-cosmos"
        },
        {
            "path": "../../packages/chain-ethereum"
        },
        {
            "path": "../../packages/chain-ethereum-viem"
        },
        {
            "path": "../../packages/chain-solana"
        },
        {
            "path": "../../packages/chain-substrate"
        },
        {
            "path": "../../packages/signatures"
        }
    ],
    "files": [
        "./src/ActionsTable.tsx",
        "./src/HomePage.tsx",
        "./src/NetworkPlot.tsx",
        "./src/SessionsTable.tsx",
        "./src/main.tsx",
        "./src/useCursorStack.ts",
        "./src/utils.ts",
        "./src/vite-env.d.ts",
        "./src/components/DidPopover.tsx",
        "./src/components/Navbar.tsx",
        "./src/components/PaginationButton.tsx"
    ],
    "include": [
        "src"
    ],
    "exclude": [
        "/Users/selkie/Development/canvas/examples/chat-explorer/lib"
    ]
}

Run tsc --traceResolution and paste its output here

File '/Users/selkie/Development/canvas/examples/chat-explorer/src/package.json' does not exist.
Found 'package.json' at '/Users/selkie/Development/canvas/examples/chat-explorer/package.json'.
======== Resolving module 'react/jsx-runtime' from '/Users/selkie/Development/canvas/examples/chat-explorer/src/ActionsTable.tsx'. ========
Explicitly specified module resolution kind: 'Node16'.
Resolving in ESM mode with conditions 'import', 'types', 'node'.
File '/Users/selkie/Development/canvas/examples/chat-explorer/src/package.json' does not exist according to earlier cached lookups.
File '/Users/selkie/Development/canvas/examples/chat-explorer/package.json' exists according to earlier cached lookups.
Loading module 'react/jsx-runtime' from 'node_modules' folder, target file types: TypeScript, JavaScript, Declaration, JSON.
Searching all ancestor node_modules directories for preferred extensions: TypeScript, Declaration.
Directory '/Users/selkie/Development/canvas/examples/chat-explorer/src/node_modules' does not exist, skipping all lookups in it.
Directory '/Users/selkie/Development/canvas/examples/node_modules' does not exist, skipping all lookups in it.
Found 'package.json' at '/Users/selkie/Development/canvas/node_modules/react/package.json'.
Using 'exports' subpath './jsx-runtime' with target './jsx-runtime.js'.
File name '/Users/selkie/Development/canvas/node_modules/react/jsx-runtime.js' has a '.js' extension - stripping it.
File '/Users/selkie/Development/canvas/node_modules/react/jsx-runtime.ts' does not exist.
File '/Users/selkie/Development/canvas/node_modules/react/jsx-runtime.tsx' does not exist.
File '/Users/selkie/Development/canvas/node_modules/react/jsx-runtime.d.ts' does not exist.
Export specifier './jsx-runtime' does not exist in package.json scope at path '/Users/selkie/Development/canvas/node_modules/react'.
Found 'package.json' at '/Users/selkie/Development/canvas/node_modules/@types/react/package.json'.
Entering conditional exports.
Saw non-matching condition 'types@<=5.0'.
Matched 'exports' condition 'types'.
Entering conditional exports.
Matched 'exports' condition 'default'.
Using 'exports' subpath './jsx-runtime' with target './jsx-runtime.d.ts'.
File '/Users/selkie/Development/canvas/node_modules/@types/react/jsx-runtime.d.ts' exists - use it as a name resolution result.
'package.json' does not have a 'peerDependencies' field.
Resolved under condition 'default'.
Exiting conditional exports.
Resolved under condition 'types'.
Exiting conditional exports.
Resolving real path for '/Users/selkie/Development/canvas/node_modules/@types/react/jsx-runtime.d.ts', result '/Users/selkie/Development/canvas/node_modules/@types/react/jsx-runtime.d.ts'.
======== Module name 'react/jsx-runtime' was successfully resolved to '/Users/selkie/Development/canvas/node_modules/@types/react/jsx-runtime.d.ts' with Package ID '@types/react/jsx-runtime.d.ts@18.3.9'. ========
======== Resolving module 'swr' from '/Users/selkie/Development/canvas/examples/chat-explorer/src/ActionsTable.tsx'. ========
Explicitly specified module resolution kind: 'Node16'.
Resolving in ESM mode with conditions 'import', 'types', 'node'.
File '/Users/selkie/Development/canvas/examples/chat-explorer/src/package.json' does not exist according to earlier cached lookups.
File '/Users/selkie/Development/canvas/examples/chat-explorer/package.json' exists according to earlier cached lookups.
Loading module 'swr' from 'node_modules' folder, target file types: TypeScript, JavaScript, Declaration, JSON.
Searching all ancestor node_modules directories for preferred extensions: TypeScript, Declaration.
Directory '/Users/selkie/Development/canvas/examples/chat-explorer/src/node_modules' does not exist, skipping all lookups in it.
Directory '/Users/selkie/Development/canvas/examples/node_modules' does not exist, skipping all lookups in it.
Found 'package.json' at '/Users/selkie/Development/canvas/node_modules/swr/package.json'.
Entering conditional exports.
Saw non-matching condition 'react-server'.
Matched 'exports' condition 'import'.
Entering conditional exports.
Matched 'exports' condition 'types'.
Using 'exports' subpath '.' with target './dist/core/index.d.mts'.
File '/Users/selkie/Development/canvas/node_modules/swr/dist/core/index.d.mts' exists - use it as a name resolution result.
'package.json' has a 'peerDependencies' field.
Resolving real path for '/Users/selkie/Development/canvas/node_modules/swr', result '/Users/selkie/Development/canvas/node_modules/swr'.
File '/Users/selkie/Development/canvas/node_modules/react/package.json' exists according to earlier cached lookups.
Found peerDependency 'react' with '18.3.1' version.
Resolved under condition 'types'.

// ...

======== Module name 'vite' was successfully resolved to '/Users/selkie/Development/canvas/node_modules/vite/index.d.cts' with Package ID 'vite/index.d.cts@5.4.11+@types/node@20.14.10+lightningcss@1.28.1+terser@5.27.0'. ========
src/HomePage.tsx:1:22 - error TS1543: Importing a JSON file into an ECMAScript module requires a 'type: "json"' import attribute when 'module' is set to 'Node16'.

1 import * as pkg from "../package.json"
                       ~~~~~~~~~~~~~~~~~


Found 1 error in src/HomePage.tsx:1

Paste the package.json of the importing module, if it exists

{
	"name": "@canvas-js/chat-explorer",
	"private": true,
	"type": "module",
	"version": "0.12.5",
	"scripts": {
		"dev": "vite",
		"build": "vite build",
		"lint": "eslint . --ext ts,tsx --report-unused-disable-directives --max-warnings 0",
		"dev:server": "tsx --tsconfig server/tsconfig.json --watch server/server.ts",
		"start:server": "cross-env NODE_ENV=production node dist/server.js"
	},
	"dependencies": {
		"@canvas-js/chain-atp": "0.12.5",
		"@canvas-js/chain-cosmos": "0.12.5",
		"@canvas-js/chain-ethereum": "0.12.5",
		"@canvas-js/chain-solana": "0.12.5",
		"@canvas-js/chain-substrate": "0.12.5",
		"@canvas-js/core": "0.12.5",
		"@canvas-js/interfaces": "0.12.5",
		"@ipld/dag-json": "^10.2.2",
		"@radix-ui/themes": "^3.1.3",
		"@vitejs/plugin-react": "^4.3.1",
		"autoprefixer": "^10.4.20",
		"cors": "^2.8.5",
		"cross-env": "^7.0.3",
		"d3": "^7.9.0",
		"date-fns": "^3.6.0",
		"express": "^4.19.2",
		"express-ipld": "^0.0.1",
		"http-status-codes": "^2.3.0",
		"react": "^18.3.1",
		"react-dom": "^18.3.1",
		"react-router-dom": "^6.20.1",
		"swr": "^2.2.5",
		"vite": "^5.4.8"
	},
	"devDependencies": {
		"@types/cors": "^2.8.17",
		"@types/d3": "^7.4.3",
		"@types/express": "^4.17.21",
		"@types/node": "^18.11.5",
		"@types/react": "^18.3.3",
		"@types/react-dom": "^18.3.0"
	}
}

Paste the package.json of the target module, if it exists

n/a

Any other comments can go here

A recent change that landed around 5.7.0 seems to break Node16 imports of .json files, because a type: json import attributed is required but also not allowed to be used: canvasxyz/canvas#404

It might be related to this issue: #59684

Which was addressed in this PR: #60019

It seems to produce new errors in these automated builds: https://github.com/search?q=repo%3Amicrosoft%2FTypeScript+%22named+imports+are+not+allowed%22&type=issues

[kirkwaiblinger]

Concise repro:

// "module": "node16", "resolveJsonModule": true, in a *.mts file (does not apply to cjs output)

// TS error: Importing a JSON file into an ECMAScript module requires a 'type: "json"' import attribute when 'module' is set to 'Node16'.ts(1543)
import something1 from './someThing.json';

// TS error: Import attributes are only supported when the '--module' option is set to 'esnext', 'nodenext', or 'preserve'.ts(2823)
import something2 from './someThing.json' with { type: "json" };

(related, #60598)

[jakebailey]

@andrewbranch

[jakebailey]

The issue is pretty poorly formatted, so to restate, the problem is that we require an import attribute for JSON in Node16 resolution, but import attributes are not allowed in Node16 resolution?

[raykyri]

That seems to be what's happening on our side, yes.

[t3chguy]

I am seeing the same thing, and even if I bump the module to nodenext that does not help as import type assertions are forbidden on import type statements

src/language-helper.ts:14:49 - error TS2822: Import assertions cannot be used with type-only imports or exports.

14 import type EN from "./i18n/strings/en_EN.json" assert { type: "json" };

src/language-helper.ts:14:21 - error TS1543: Importing a JSON file into an ECMAScript module requires a 'type: "json"' import attribute when 'module' is set to 'Node16'.

14 import type EN from "./i18n/strings/en_EN.json";

[andrewbranch]

In Node.js 16, JSON files can’t be imported without an import assertion, and import attributes aren’t supported until 18 (I’m ignoring odd-numbered versions). It seems like it was a bug/oversight to allow JSON imports without assertions in --module node16, but I don’t think we want to suggest anyone use import assertions now. I guess we should just make #60019 have no effect on node16, even though node16 seems to have been incorrect all along. Node.js v16 is EOL now, so I think we should deprecate --module node16 and make a --module node18 that enforces use of import attributes for JSON imports (like nodenext does now).

[kirkwaiblinger]

@andrewbranch In principle, this resolution makes sense to me. However, I think the docs are problematic here.

I have it ingrained into my head, and I'm guessing that many users do as well, that that the *Next settings are more or less aliases of their latest concrete version.

The TS docs have this:

nodenext: Currently identical to node16, but will be a moving target reflecting the latest Node.js versions as Node.js’s module system evolves.

...and this:

node16 and nodenext are currently identical, with the exception that they imply different target option values. If Node.js makes significant changes to its module system in the future, node16 will be frozen while nodenext will be updated to reflect the new behavior.

It seems like nodenext is already a nontrivial departure from node16 in undocumented ways. My request as a user, having spent many hours tracking down issues of which this issue and #60598, are the root causes, and
not having thought to exhaustively check node16 vs nodenext in addition to all the other relevant settings, would be that

1. the docs be quite clear going forward on all differences between the highest concrete version and the *.next versions of settings (including lib/target/module/modluleresolution ESNext/nodenext).
2. concrete versions be pinned more frequently (like the proposed node18 in this issue) when nontrivial departures occur, so that users can actually use potentially-necessary features without relying on an unstable setting.

The reason I say this here, rather than immediately spinning off a new issue, is that I note that this is marked for TS 5.7.3, and I worry that subtly dropping module: Node18 in a patch version is not enough fanfare to break through to users who may be wasting hours not knowing they're running into a node16/node18/nodenext discrepancy. Furthermore, there may be other undocumented node16 vs nodenext discrepancies that would have to be included in a stable node18 module version. I don't know.

So I'm curious what the gameplan for actually fixing and communicating this issue out is.

[kirkwaiblinger]

To be concrete, it seems to be that this can (and should) be done in a patch change, 👍

In Node.js 16, JSON files can’t be imported without an import assertion, and import attributes aren’t supported until 18 (I’m ignoring odd-numbered versions). It seems like it was a bug/oversight to allow JSON imports without assertions in --module node16, but I don’t think we want to suggest anyone use import assertions now. I guess we should just make #60019 have no effect on node16, even though node16 seems to have been incorrect all along. Node.js v16 is EOL now, so I think we should deprecate --module node16...

but I would add that I think that import attributes also should be allowed in node16, since otherwise users of >=node18 can only use the "unstable" nodenext.

It's this part that I'm worried about dropping in a patch version (even though, as a user, I do want it ASAP 🙂):

...and make a --module node18 that enforces use of import attributes for JSON imports (like nodenext does now).

[andrewbranch]

No option will ever be dropped in a patch version. In fact, our current policy is that no option ever be dropped without a deprecation, and nothing ever be deprecated without a major version bump, which occurs once every 2.5 years.

[kirkwaiblinger]

Great! So, would the thought be that a patch include

1. a lenient "module: node16" that permits all of
   1. no import attributes/assertion at all
   2. import assertion
   3. import attributes
2. unchanged "module: nodenext"
3. potentially docs changes highlighting that this area is a meaningful discrepancy between node16 and nodenext

and the next minor include

1. "module: node18" that requires JSON import attributes, and prohibits import assertions.
2. No behavior changes to the "module: node16", which at this point will be in an extra-wrong state of permitting import attributes (extra-wrong due to the existence of node18 at this point). Or would import import attributes be re-banned at this point?

Sorry for pestering on this, but the expected resolution here informs some decision-making for me (on a node18 project that also needs to be upgraded from 'commonjs' to 'node16'/'nodenext') on whether to move it to

• TS 5.6/node16
• TS 5.7/nodenext, later TS 5.8/node18
• (wait for) TS 5.7.3/node16
• (wait longer for) TS 5.8/node18